This invention refers to an auxiliary assembly element for machine parts which have to be connected with the machine with the aid of additional mounting devices, consisting of an auxiliary element which may be attached to and easily removed from the machine part, and which may be removed after the assembly is completed. This invention concerns particularly an auxiliary assembly for housing sealing covers with integrated radial shaft sealing ring and through holes for mounting screws, particularly for crank shafts, cam shafts, and gear housings of combustion engines, consisting of a base element which extends essentially radially with at least one axially extending ring-shaped projection for the concentric accommodation of the housing sealing cover.
In order to mount machine parts it is required that the machine part to be mounted is moved to the machine in true position and is then connected with it. The connection of such machine parts often occurs by using mostly standardized mounting elements, such as rivets, screws, clamp pins, etc. While in the construction of large machinery, the assembly of machine parts takes place mostly manually, possibly with the help of special holding tools, where the mounting tools after assembly are moved into their mounting position individually and most of the time by hand, the mass production of machine housings, such as electric motors, combustion engines, control gears, etc., presents special requirements for the possibility of automatic mounting.
In the construction of motor vehicles in particular, the housing sealing covers, for instance, which have to be mounted with several screws on the motor or gear housing, are moved to the mounting location and also positioned there and screw connected, with automatic tools, such as industrial robots. This requires that the housing sealing covers may be removed from storage in position-oriented position and may be transported to the motor or gear housing, resp., while the mounting screws should also be transported in true position together with the housing sealing cover, if possible.
In DE-PS DE 42 17 131 a housing sealing cover for a crank shaft housing for combustion engines is described, in which the mounting screws are kept friction-locked in the screw through-holes of the housing sealing cover so that when the housing sealing cover is moved to be attached to the crank shaft housing the mounting screws are automatically also moved into the screw position. While the screws for the mounting of the housing sealing cover are directly available, the friction-locked connection of the screws in the bore holes of the housing sealing cover is problematic, however, as is the necessary positioning of the screws in the direction of the threaded holes of the machine housing during the mounting process. In addition, the housing sealing covers which are equipped with such screws cannot be stacked and are therefore not suitable for automatic pick-up by industrial robots.
Finally in housing sealing covers with a shaft extending through the cover in the assembly stage, which require additional sealing, the automatic mounting is made more difficult because the sealing lip of the radial shaft sealing ring integrated in the housing sealing cover must be radially expanded when the cover is moved onto the motor shaft.
In addition, an auxiliary assembly element is known from EP-PS 0 272 775 which is designed to make the mounting of a housing sealing cover with integrated radial shaft sealing ring easier. The auxiliary assembly element consists essentially of a base element of plastic materials which extends radially and with a radial cylindrical shell fastened on the inside to support the sealing lip of the radial shaft sealing ring, especially to push the housing cover with its sealing ring onto the end of the shaft. In addition, the auxiliary assembly element has a radial outer second axial ring-shaped cylinder projection, which encloses a corresponding recess of the housing sealing cover and thereby ensures a centric position of the sealing lip of the radial shaft sealing ring. The housing sealing cover is attached in assembled condition with the crank shaft housing of a combustion engine via several screws. The mounting screws have to be supplied separately after positioning and alignment of the housing sealing cover.
The invention is based on the task to simplify the assembly of machine parts which are connected via additional mounting devices with the machine housing, and primarily to permit fully automatic mounting by industrial robot. This includes safe transport and storage of such machine parts.
This task is accomplished in accordance with the invention by an auxiliary assembly element, which is equipped with supports for a position-oriented accommodation and arresting of the mounting devices. The use of an auxiliary assembly element does increase the production costs of the machine parts because an auxiliary assembly element must be made available and connected with the machine part. The possibility of multiple use of such auxiliary assembly elements, however, keeps these additional costs limited. The big technical and economic advantage is that the mounting devices for the machine part are held by the auxiliary mounting element in such a position that, after moving the machine part into the assembly position, the mounting devices are available in true position and may be moved into their functional mounting position.
Preferably the auxiliary assembly element consists of a plastic element which may be produced with a spray process simply and inexpensively in a form which is adjusted to the machine apart. Such an auxiliary assembly element has a low weight and may be used multiple times.
The auxiliary assembly preferably consists of a base element extending in the primary level of the machine part from which projections protrude which enclose the machine part and/or reach into the machine part, and which may be connected to and easily removed from the machine part. A plug-in connection is usually sufficient and easily managed.
In addition, it is suggested that supports in the form of through-holes are provided in the auxiliary assembly element for the mounting devices into which the mounting devices may be moved and positioned so that they may be inserted. This ensures that the mounting devices may be picked up during assembly by a common tool and may be moved through the auxiliary assembly element into the connection position with the machine housing.
In order to prevent the loss of a mounting device during transport and storage, it is suggested that the through-holes in the auxiliary assembly element are equipped with arresting aids so that the mounting devices may be accommodated and removed. In addition, it appears to be advantageous if the through-holes have additional guiding aids for the positioning during transport and storage as well as for the supply of the mounting devices into the machine part in true position during assembly.
In addition, it is suggested that the extension of the auxiliary assembly element corresponds approximately to the length of the mounting devices. This ensures that the mounting devices do not project from the auxiliary assembly element during transport and storage. This permits that the auxiliary assembly elements with the machine parts may be stacked. This is particularly significant when the auxiliary assembly element including machine part is picked up by an industrial robot.
In the known auxiliary assembly elements of plastic materials for housing sealing covers with integrated radial shaft sealing ring and through-holes for mounting screws, particularly for crank shaft, cam shaft, and gear housings of combustion engines, consisting of an essentially radially extending base element with at least one axially extending ring-shaped projection for concentric accommodation of the housing sealing cover, it is suggested that the auxiliary assembly element is equipped with supports to accommodate and position the mounting screws so that they are position-oriented. According to the invention the known auxiliary assembly elements for housing sealing covers are improved to the extent that the mounting screws may be received by the auxiliary assembly element in true position and are held in this position during transport and storage up to the time of assembly, in order to be screwed directly through the housing cover hole into the threaded hole of the crank shaft or gear housing, resp., by using a common tool. Preferably a collar in the radial outer circumference of the auxiliary assembly element which is axially angled is provided during assembly as support against the crank shaft housing. This is advantageous when the mounting screws are pressed axially out of the supports of the auxiliary assembly element into the threaded holes of the crank shaft housing.
An additional design of the invention provides that the support to accommodate one mounting device consists of one each essentially axially positioned, radially elastic extendable projection with a through-hole for one mounting screw. When the mounting screw is moved into the through-hole, the projection expands radially elastically and holds it after the projection has sprung back.
According to an additional characteristic of the invention, the projection may be made elastic resilient by axially running slots or similar. This results in tongue-shaped projections. Preferably each support consists of at least three tongue-shaped, essentially axially aligned projections. The latter preferably have recesses to house and arrest the screw head. These recesses are designed such that the head of the mounting screws may be pressed in and out.
Advantageously, mounting screws with parts which project radially beyond the screw head, such as protuberances, flanges, shoulders, or similar, are used while the radially projecting parts, such as the shoulder of a shoulder head screw, may be pressed in and out of the recesses.
In addition, the design of the axially aligned projections is advantageous with extensions, which extend in the direction of the screw shanks. This ensures a centric support of the mounting screw shanks, and the screws are held in exactly aligned position so that during assembly the screws are held centric to the threaded holes of the crank shaft or gear housing, resp., in the auxiliary assembly element.
In addition, the invention suggests that in the auxiliary assembly element centering lugs are provided which extend axially beyond the picked-up machine part or the picked-up housing sealing cover, resp., in the direction of the machine housing, and which during assembly, particularly when the parts to be mounted are joined, permit that the parts are arranged position-oriented to each other. It is not significant whether the centering lugs reach into corresponding cut-outs in the machine housing or whether the centering lugs orient themselves on projecting edges of the machine housing during assembly. For a clear positioning or centering, resp., of the parts at least two centering lugs should be provided on the auxiliary assembly element.
Finally, it seems appropriate to attach arresting clamps on the auxiliary assembly element for a correctly positioned connection with the machine part or with the housing sealing cover, resp., where several arresting clamps increase the precision in regard to positioning. Centering lugs and arresting clamps may be combined such that the centering lug is part of the arresting clamp.